Which hormone plays a crucial role in animal aggression during a conflict?

The hormone that plays a crucial role in animal aggression during a conflict is testosterone. This hormone is known to influence aggressive behaviors in many species, including both male and female animals. Higher levels of testosterone are correlated with increased aggression, particularly in contexts such as competition for resources, establishing dominance, or during mating disputes.

Testosterone affects the brain regions that regulate aggression, leading to increased assertiveness and the potential for aggression when faced with threats or challenges. This is seen in various studies of both domestic animals and wild species, where manipulations of testosterone levels can change aggression levels significantly.

While estrogen, norepinephrine, and progesterone have roles in the broader spectrum of animal behavior, they are not primarily recognized as the hormones driving aggression to the extent that testosterone is. Thus, testosterone is the hormone that is most directly associated with aggression during conflict situations among animals.